Elimination of impurities in insulating oils



' Dec. 10, 1929. C, J, RODMAN y 1,739,092

ELIMINATION OF IMPURITIES IN INSULATING OILS Filed Oct. 21. .1924

Y l ATTORNEY Patented Dec. 10, 1929 UNITED STATES PATENT OFFICE l CLARENCE J' RODMAN, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC & MANUFACTURING VANIA COMPANY, A CORPQRATION F PENNSYL- ELIMINATION 0F IMIPURITIES IN INSULATING OILS Application led October 21, 1924. Serial No. 745,042.'

My invention relates to oil-immersed electrical devices and particularly to means for eliminating the impurities in the oil used in such devices.

One object of my invention is to provide an oil-insulated electrical translating device having means for causing an inert gas to bubble through the insulating oil for purifying it.

Another object of my invention is to provide an oil-immersed electrical translating device that shall have a small amount of inert @as gently bubbling through the insulating oil for the purpose of purifyingr it.

A further object of my invention is to provide an oil-insulated electrical translating device having means for continually purifying the insulating oil.

In oil-immersed electrical devices, such as circuit interrupters and transformers, the dielectric strength of the insulating oil gradually decreases by reason of the accumulation of impurities, such as water, carbon and oil sludge, or other decomposition products. The

-accumulation of such undesirable ingredients vice, together with the surface area that is exposed to the atmosphere and many other conditions, the originof some of which has not been definitely determined. l

I have found that, by bubbling an `inert gas, such as dry carbon dioxide, or nitrogen, through the insulating oil, it is possible to remove a large percentage of the water; sweep out any highly volatile solvents and coagulate or agglomerate many of the finely divided bodies, such as carbon or resins.

The single figure of the accompanying drawings is a view, partially in elevation and partially in section, of a trans-former embodying my invention.

My invention comprises, in general, an electrical translating 'device l containing windings 2 of a transformer and a body of insulating fluid 3, such as petroleum oil, as well understood in the art, surrounding the windings 2, together with a pipe network 4 Vfor liberatinggas near the bottom of the translating device 1 injsuch manner'that the liberto a volume insuflicient to cause excessive bub- K bling at the upper surface of the insulating fluid 3.

A container G that is filled with compressed i carbon dioxide, nitrogen, or mixtures of such gases, supplies gas to the network 4 through a regulating valve 7 to a dehydrator 8 that, in turn, is connected to a telltale 9 in a pipe line 11. The telltale 9 contains a suitable liquid for the purpose of giving a visual indication .of the flow of gas from the container 6 to the electrical translating device 1. A suitable breathing regulator l2 is providedfor the translating device 1. 4

The pipe line 11 is preferably provided with a suitable check valve 13 in order to prevent oil from being forced back into the ,telltale 9 and dehydrator 8 and regulating valve 7. The insulating oil 3 in the translating device should not contain over one-thousandth part of one percent of water, whereas ordinary commercial carbon dioxide contains about two-hundredths of one percent of water. Accordingly, it is necessary toprovide the system with the dehydrator 8f In operating an electrical translating device according to my invention, a cylinder of gas weighing about fifty pounds is connected to the regulating valve 7 that is adjusted to liberate approximately 20 cu. centimeters of gas per minute. Under these conditions, the tank needs to be replaced about onceper year. However, the amount of gasliberated in the translating device must be varied in accordance with the working conditions and the cubic capacity of the particular device. The gas, in passing upwardly through the insulating oil 3, takes up a percentage of the water found therein as well as certain of the volatile solvents. At the same time,4the gas as. ifi/e coagulates or agglomerates certain of 'the more nely divided loodies, such as carhon or resin, and deposits them as a precipitate, thereby improving the dielectric qualities ot the oil and continually7 purifying such oil hy preventing the accumulation and assisting in the disintegration ot the impurities commonly termed oil sludges.

ln electrical translating` device containing oil-purifying apparatus embodying; my invention materially prolongs the lite of the insulating medium and sustains its dielectric Strength hy the process of causing a dry, inert, or practically oxygen-tree, gas to loulohle therethrough. The bubbling gas serves to remove Water, precipitate the sludge, and to prevent the 'formation of other products et decomposition of oil incidental to the operation oit oil-immersed electrical translating devices. ll do not Wish to he restricted to the specific arrangement ot parts herein set forth, as various modifications thereof may he ettected Without departing trom the spirit and scopeot my invention. ll desire therefore that only such limitations shall he imposed as are indicated in the appended claims.

ln the appended claims, the expression inert gas shall he understood as comprehending gas 'from Which oxygen has heen or is largely or substantially excluded.

ll claim as my invention:

l. lin the art et purifying the insulating; oil of an electrical translating device, the step 'whichl consists in passing an inert gas into coacting relation with said medium to preserve its dielectric characteristics.

2. ln the art of purifying/the insulating` oil of an electrical translating device, the step Which consists in bubbling an inert gas through said oil to preserve its dielectric characteristics.

3. ln the art of purifying the insulating oil of an electrical translating device, the

step which consists in bubbling dry carhondioxide gas through said oil to preserve its dielectric characteristics.

4.. In the art of dehydrating the insulating oil of an electrical device, lthe step which consists in bubbling /a dehydrated inert gas 'through said oil to preserve its dielectric characteristics.

5. ln the art of dehydrating the insulat ing oil of an electrical device, the step Which consists in bubbling dry carbon-dioxide gas throughfsaidv oilto preserve its dielectric characteristics.

In testimony whereof, ll have hereunto suhscribed my name this 14th day of fctoloer,

CLARENCE el.. RDMAN. 

